Aj. Castrotirado et al., DISCOVERY OF THE OPTICAL COUNTERPART OF THE SOFT-X-RAY TRANSIENT GRO J0422+32, Astronomy and astrophysics, 276(2), 1993, pp. 37-40
We report the discovery of the optical counterpart of the type II Soft
X-ray Transient. GRO J0422+32, on 1992 August 15, ten days after the
outburst, as well as the optical light curve during the first 100 days
after the outburst, making GRO J0422+32 the slowest one in the optica
l decline. Archival plates searches show that the object did not under
go a similar outburst after 1928. Its optical and X-rav evolution is s
imilar to other members of its class, like V616 Mon, V404 Cyg and GRS
1124-68. For these later three there are dynamical evidences that plac
e them among the best black holes candidates so far. These similaritie
s suggest that the compact object in GRO J0422+32 may also be a black
hole.